Methods and apparatus for determination of halohydrocarbons

ABSTRACT

A real-time, on-line method and analytical system for determining halohydrocarbons in water which operate by (1) extracting on-line samples; (2) purging volatile halohydrocarbons from the water (e.g., with air or nitrogen); (3) carrying the purge gas containing the analytes of interest over a porous surface where the analytes are adsorbed; (4) recovering the analytes from the porous surface with heat (thermal desorption) or solvent (solvent elution) to drive the analytes into an organic chemical mixture; (5) generating an optical change (e.g., color change) in dependence upon a reaction involving the analytes and a pyridine derivative; and (6) measuring optical characteristics associated with the reaction to quantify the volatile halogenated hydrocarbon concentration.

This application is a continuation of U.S. patent application Ser. No.16/004,189, filed on Jun. 8, 2018, for “Methods and Apparatuses forDetermination of Halohydrocarbons.” In turn, U.S. patent applicationSer. No. 16/004,189 is a continuation of U.S. patent application Ser.No. 14/819,454, filed on Aug. 6, 2015, for “Methods and Apparatuses forDetermination of Halohydrocarbons” (issued on Jul. 10, 2018 as U.S.patent Ser. No. 10/018,567). In turn, U.S. patent application Ser. No.14/819,454 is a continuation of U.S. patent application Ser. No.13/640,312, filed on Oct. 9, 2012 (issued on Sep. 15, 2015 as U.S. Pat.No. 9,134,290), which is a national stage entry under 35 U.S.C. § 371 ofPCT Application No. PCT/US11/32438, which claims priority to U.S.Provisional Application No. 61/326,717, filed on Apr. 22, 2010. Each ofthe aforementioned applications names a first inventor of Harmesh K.Saini, and each of the aforementioned applications is herebyincorporated by referenced.

The present invention relates to measurement of halohydrocarbons inaqueous solutions. More particularly, this disclosure provides methodsand devices that can be used for on-line measurement of trihalomethanes(THMs) in water, based on a modified Fujiwara-type reaction.

BACKGROUND

Potable water producing utilities disinfect the water by the addition ofhalogenating agents (halo is a prefix for chlorine, bromine and iodine).While these agents are beneficial to killing illness bearingmicroorganisms, they unfortunately also produce various halogenateddisinfection by-products (DBPs) such as trihalomethanes (THMs),haloacetic acids, haloaldehydes, haloacetones, haloacetonitriles andchloral hydrate. THMs, in particular, head the USA EPA list of toxic andcarcinogenic compounds highly regulated in drinking water. THMs as agroup include chloroform (CHCl₃), bromodichloromethane (CHBrCl₂),dibromochloromethane (CHBr₂Cl) and bromoform (CHBr₃). These 4 THMs areincluded among the 25 volatile organic compounds regulated under theSafe Drinking Water Act (SDWA) of 1974.

In 1979, the US Environmental Protection Agency (EPA) set the maximumtotal contaminant level of 100 parts per billion (ppb) for the 4 THMs.The Stage 1 Disinfectant and Disinfection Byproduct Rule announced in1998 updates and supersedes the 1979 regulations for totaltrihalomethanes by lowering the total THMs regulatory limit to 80 ppb.Recently the American Water Works Association (AWWA) data base reportedthat a safety margin of 15% below the regulatory limit for total THMsshould be targeted. The Safe Drinking Water Act (SDWA) in 1996 requiresthe EPA to develop rules to balance the risks between microbialpathogens and disinfection byproducts (DBPs). It is important tostrengthen protection against microbial contaminants, and at the sametime, reduce the potential health risks of DBPs.

Subsequently, various methods and apparatus were developed for themeasurement of halohydrocarbons, especially THMs, in aqueous solutions.Traditional analytical methods used to quantify THMs in water are basedupon gas chromatography (GC) equipped with an electron capture detector(ECD) or a mass-spectrometer (MS). In this method, water samples aretypically collected in vials and brought to an offsite laboratory toanalyze by GC-ECD or GC-MS. Individual compounds are determined and thesum of all 4 THMs constitute total THMs (TTHM). This process is verylaborious and time consuming.

In the literature, a simpler chemical method cited to determine totalTHMs in water is based upon colorimetric determination. In this method,when pyridine is reacted with THMs in a strong alkaline solution, a redcolor is formed. The intensity of the color is determined using anoptical spectrometer. The color intensity produced is proportional tothe total amount of THMs present in the sample. This method is calledthe “Fujiwara reaction” (K. Fujiwara, Sitzfer, Aohandl. Naturforsch.Ges. Rostock, 6, 33, 1941; G. A. Lugg, Anal. Chem., 38, 1532, 1982; T.Uno et al. Chem. Pharm. Bull., 30, 1876, 1982).

Fujiwara reactions can, however, present certain problems, as pyridinecan be insoluble in some reagents used to make the medium alkaline. Forexample, when using an inorganic base such as NaOH or KOH, it isdifficult to diffuse OH⁻ ions from the aqueous phase into the pyridineorganic phase. Since the diffusion of OH⁻ ions is difficult to control,the results are not easily reproducible.

Most of the above methods and apparatus described in the literature formeasurement of halohydrocarbons require expensive equipment, itself withsubstantial maintenance demands, extensive personnel training, andsignificant turn-round time (12-24 hours), or expose the operator tonoxious chemicals. The present invention addresses the need for a lowcost, simple, reliable, automated and on-line real-time method tomeasure THMs in water.

SUMMARY OF THE INVENTION

This disclosure provides a low cost, simple, reproducible, on-line,real-time method and apparatus to measure halohydrocarbons,particularity THMs, in an aqueous solution. The disclosed techniques arebased upon an improved chemistry for a reproducible Fujiwara-typereaction, i.e., via a modified Fujiwara reaction.

One objective of the present invention is to modify the chemistry toovercome the deficiencies of the basic Fujiwara reaction. The mainconstituent of the traditional Fujiwara reaction is pyridine. In theembodiments presented below, a pyridine derivative is instead used; thisderivative can be selected from a group of substituted pyridines (e.g.,on C₁-C₅, including nicotinamide and its derivatives, alkylpyridines,azapyridines and quinoline derivatives). Ideally, the reaction chemistryis selected to minimize the odor and exposure concerns of pyridine, asin the traditional Fujiwara reaction. The pyridine derivative canoptionally be dissolved into a suitable solvent, such as alcohols(butanol is a suitable example), acetonitrile, or ethers such as THF.The Fujiwara reaction can be further modified by mixing an organic baseand water to form a one-phase reaction solution, increasing reliabilityof the results. The organic base can if desired be selected from thegroup of tetraalkylammonium hydroxides, including methyltributylammoniumhydroxide, tetramethylammonium hydroxide, tetrabutylammonium hydroxideand tetrapropylammonium hydroxide.

Another purpose of this disclosure is to provide an improvedimplementation of the Fujiwara process, specifically by optimizing thetiming of two (or more) absorbance measurements, for the purpose ofmeasuring the chloroform concentration and the total THM (TTHM) contentin a water sample. A method is disclosed whereby the individualconcentrations of all four THM components in a potable water sample canbe determined, enabling sophisticated control processes, tracking,diagnostics, alarms and other processes.

Further aspects of the invention provide a device that can be installedin-situ to periodically and automatically measure halohydrocarbonpresence in a test sample, for example, a municipal water supply. Theresults can be automatically logged into a database for monitoring,compliance or other purposes, and can be transmitted if desired over anetwork (such as the internet) to a central control or reportingstation, for example, that monitors multiple such devices.

Further aspects of the described technology will become clear from thedescription below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a block diagram of an embodiment 101 of a method andsystem for measuring halohydrocarbons using a modified Fujiwarareaction.

FIG. 2 provides a block diagram of an embodiment 201 that uses anin-situ mechanism to monitor halohydrocarbon presence. As represented bydashed lines, the embodiment may optionally feature in-situ maintenanceand calibration using local storage for reagents, fluids and othermaterials used in operation of the system; additionally, the in-situmechanism may be part of a remote monitoring system that monitors anetwork of several such mechanisms.

FIG. 3 provides a block diagram of an embodiment 301 of a system ordevice for measuring halohydrocarbons, THMs in particular.

FIG. 4 is a graph 401 used to explain computation of concentration ofindividual THMs, based on two time-based optical absorbancemeasurements.

FIG. 5 provides an embodiment 501 of an in-situ device for measuringhalohydrocarbons, for example, an on-line device for measuringhalohydrocarbon presence in potable water, on a real time basis.

FIG. 6 provides an embodiment 601 similar to the embodiment seen in FIG.5 .

FIG. 7 is a graph 701 that depicts the relationships of the relativeratios of the four THMs measured in a historical set of 40 drinkingwater samples collected from several geographically dispersed waterutilities in the UK.

FIG. 8 is a graph 801 that depicts the time-dependent opticalabsorptivity coefficients of two Fujiwara reaction solutions, onecontaining chloroform and the other a mixture of the three brominatedTHMs.

FIG. 9 is a flowchart 901 relating to calculation of individual THMconcentrations based on measurements, such as those presented in FIG. 8, and expected THM ratios such as those depicted in FIG. 7 .

FIG. 10 is a system diagram 1001 used to explain a method of remotelymonitoring one or more in-situ mechanisms.

DETAILED DESCRIPTION

In several of the embodiments presented in this disclosure,halohydrocarbons can be measured in four steps: 1) extracting an on-linesample and purging out volatile halogenated hydrocarbons from the samplewith air or nitrogen—the purge gas may be used to carry analytes ofinterest over a porous absorbent surface; 2) recovering concentratedanalytes from the adsorbent surface using one of several alternativeprocesses, such as using heat (thermal desorption) or solvent (elution),to transfer the concentrated analytes into a chemical mixture (e.g.,into a reaction medium); 3) causing a Fujiwara-type reaction—asmentioned, the specific reaction used involves several modifications tothe traditional Fujiwara process; 4) reading the optical absorbance ofthe red color formed by the chemical reaction of THMs in the reactionmixture to quantify THM concentration(s).

The measurement of halohydrocarbons can be important in many contexts,among them regulation of a potable water supply, such as a municipalwater supply. The embodiments presented in this disclosure facilitate adevice and related method that can be use for in-situ measurement ofhalohydrocarbons, that is, without requiring special personnel trainingor experience normally associated with manual field usage of amass-spectrometer or electron-capture detector or other sophisticatedequipment. Through the use of a modified Fujiwara-type reaction, that isone that uses a pyridine derivative instead of pyridine and, optionally,a single-phase reaction, the embodiments presented herein provide asystem that can be repeatedly cycled with little maintenance and withreduced exposure to noxious fumes and hazardous chemicals, and withrelatively greater accuracy and reliability. As the embodimentspresented herein can be used in-situ, under control of an electroniccontrol system (e.g., a computer), these embodiments facilitate (a) aremote monitoring system (e.g., via a local area network or “LAN,” orover the internet, with results reported to a central monitoringsystem), and (b) consequent greater accuracy and improved data retentionfor compliance and monitoring purposes.

FIG. 1 provides a block diagram of an embodiment 101 of a method andsystem for measuring halohydrocarbons using a modified Fujiwarareaction. A sample is first processed to extract at least onehalohydrocarbon to an adsorbent medium, as indicated by step 103. Afterbeing concentrated on the adsorbent medium, the halohydrocarbons aretransferred to a reaction medium having a pyridine derivative, asreferenced by numeral 105. In addition to the pyridine derivative, thereaction medium may be an organic solution used to elute the analytesfrom the adsorbent medium (such as acetonitrile). Alternatively, theanalytes may be removed by a thermal desorption process, such as byheating the adsorbent medium to a point where the analytes becomevolatile, and then sweeping the volatile analytes into the reactionmedium using gasses such as nitrogen or air. As depicted by referencenumeral 107, the analytes are subjected to a modified Fujiwara reaction,based on an organic developing agent (such as the hydroxide of anorganic cation) and an optional organic solvent, at a controlled,elevated temperature (e.g., present in the medium mentioned earlier). Asthe reaction proceeds, the color intensity of the reaction mediumchanges, and this optical property is measured during the reaction, pernumeral 109. Based on the measured optical results, halohydrocarbonconcentration is determined, as indicated by reference numeral 111.

In fact, there may be several halohydrocarbons (e.g., THMs) present inunknown quantities, and the system of FIG. 1 may therefore optionally beapplied to discriminate between the THMs and to determine theirindividual concentrations. As indicated by dashed-line (i.e., optional)process block 113, the optical properties of the reaction medium may bemeasured two or more times, at different times, to detect the change incolor intensity. As will be presented below, based upon predetermineddata, total THM presence may be determined and individual THMconcentrations determined from this data based on on-line or real-timemeasurements.

FIG. 2 introduces a system embodiment 201, including a business method,which may rely on the embodiment of FIG. 1 . In particular, an in-situapparatus may be used to test for at least one halohydrocarbon, based ona modified Fujiwara process as just described and as reference bynumeral 203. Because a modified chemical process is used, includingoptional automation, the system may be performed in-situ and may helplimit worker exposure to noxious fumes or hazardous chemicals, andprovide greater accuracy relative to phase-separated reactions. Based onthe measurements, concentration of at least one halohydrocarbon isdetermined (per numeral 205). The results may be electronically storedin a database, indexed by time, thereby serving the compliance goalsreferenced above, e.g., a log may be generated and kept to showcompliance and to track situations and times when detected substancesexceed desired levels, as alluded to by numeral 207.

FIG. 2 also references several optional steps. First, the use ofpyridine derivatives and relatively safe chemicals facilitates localmaintenance, e.g., materials used for the reaction may be stored inlocal reservoirs and occasionally replenished, with waste materialsbeing collected and safely disposed. Relatively easy maintenancefacilitates in-situ systems without requiring extensive training ofpersonnel. Second, materials that degrade over time may be recalibratedand used until they need to be replaced using one or more locally storedcalibration media (i.e., one or more “standards”); as will be presentedbelow, for example, an electronic control system may be used to run thesame steps used to test the potable water supply with each locallystored calibration test medium (e.g., on THM-free water);self-calibration further enhances the ability to provide and effectivelyuse in-situ devices for monitoring chemicals such as THMs. Finally, forembodiments that use computer control of the various sampling andtesting steps according to a predetermined schedule, a LAN or internetconnection may also be provided for transmitting measurement results toa central monitoring facilities, e.g., a regulatory agency, regionalwater management station, or some other type of entity, therebyproviding for enhanced ability to continuously monitor chemical levelsand quickly respond to problems. In this case, data from the particularin-situ machine can be indexed by various factors, including time ofmeasurement, particular THM values, an identifier of the particularmachine that produced the data, location, etc. This data may be loggedeither in a dedicated file, or as part of a database used to trackseveral of the on-line mechanisms. These options are variously indicatedby numerals 209, 211 and 213 in FIG. 2 . If desired, the determinationof THM amounts may be compared to one or more thresholds, as indicatedby dashed line “options” block 215, with action (217) being responsivelytaken depending on this comparison. An alarm (219) may be generated ifTHM concentrations exceed desired level; alternatively, an electroniccontrol system may responsively and automatically adjust upstream watertreatment processes, either by increasing or decreasing the use ofcertain chemicals, to provide for a sanitized water supply withoutexceeding recommended THM norms, as collectively represented by block221. Individual THM species contributions may also be used in diagnosingissues associated with the water treatment process.

With several principal features of the present disclosure thusintroduced, additional detail will now be presented, with reference toFIGS. 3-10 .

FIG. 3 presents a block diagram of an embodiment 301 of a system ordevice that may be used for in-situ measurement of halohydrocarbons. Inparticular, a potable water supply 301 is to be monitored toperiodically determine the presence of halohydrocarbons. In oneembodiment, monitoring may occur taken at frequent intervals, forexample, every hour, around the clock. The water supply 303 may be forexample a particular point in a municipality's or water company'sdistribution network. At each monitoring interval, a sample may beextracted from the potable water supply and transferred to a vessel 305.The sample extraction may be part of an on-line mechanism 307 thatautomatically draws a predetermined volume of water into the purgevessel. Halohydrocarbons are then extracted from the water test sampleand transferred to a column trap 309, which contains the adsorbentmedium previously referred to (e.g., a porous medium). This extractionmay be accomplished by passing gas through the water test sample, andadsorbing the analytes extracted by the gas to the adsorbent medium, asindicated by numeral 311, or by directly passing the test water throughthat medium. Once the processing of the test water sample is complete,the now-concentrated analytes are again transferred, using a thermal orfluidic transfer process, to a reaction vessel, per numeral 313 and 315.As indicated earlier, a fluidic process may use a solvent to flush theanalytes from the adsorbent medium, and an alternative thermal processmay simply heat the analytes, and pass them through a reaction medium(e.g., organic solvent), to force the analytes into solution at roomtemperature. When the proper reaction mixture is ready (i.e., thereaction medium, post introduction of a pyridine derivative and organicdeveloping agent, such as an organic base), the single-phase mixture ormedium is then heated in a controlled manner which causes the reactionto progress; a thermal control unit 317 may be used for this purpose.The reaction produces a color that changes in intensity dependent uponthe time of the reaction, the temperature and the concentrations of thehalohydrocarbons present in the reaction medium; the intensity change isoptically measured, for example, by determining the optical transmissionthrough the reaction medium at a specific wavelength, and an opticalmeasurement device (e.g., an optical spectrometer) may be used for thispurpose, as indicated by 319. At one or more times as the reactionproceeds, the optical measurement may be repeated, with the time andtransmission at the specific wavelength used to determine chloroform andtotal THM presence. Once the last measurement has been taken, thereaction well can be emptied, per numeral 321, and the system can beprepared for testing at the next monitoring interval, as indicated bynumeral 329.

FIG. 3 also illustrates a computer 325, control software 327, and anumber of control arrows to show that the computer can act as anelectronic control system for automating the steps (and associatedtiming) of each of the elements referred to above. Specifically, thecomputer can be controlled according to a predetermined time schedule orremotely, on a dynamic basis, to automatically perform testing stepsfrom test sample extraction, from to THM calculation to system cleaning,all without human intervention. If desired, optical test results canalso be relayed to a remote location, with THM concentration calculationbeing remotely performed.

As indicated, one feature of embodiments presented in this disclosure isthe use of a modified chemical process to overcome the deficiencies ofthe basic Fujiwara reaction. The main constituent of the traditionalFujiwara reaction is pyridine. In the embodiments discussed above, apyridine derivative is selected from a group of other substitutedpyridines, including nicotinamide and its amide-alkylated derivatives,and alkylpyridines such as 3-picoline. The reaction chemistry does notshare the strong odor of pyridine, as in the basic Fujiwara reaction,and is safer to use. Suitable criteria for selecting a pyridinederivative include identifying a material that (a) is based on apyridine ring structure with one or more of the hydrogen atoms in thering structure replaced, (b) possesses less noxious characteristics(smell, hazardous exposure) of pyridine, (c) is not volatile, (i.e., hasa boiling point greater than the associated reaction temperatures, e.g.,greater than 80° C.), and (d) is consistent with proper progression ofthe Fujiwara-type reaction, that is, the reaction induces a colorintensity change in reaction with halohydrocarbons. The pyridinederivative can be dissolved into an organic solvent such as methanol,butyl alcohol, or acetonitrile. The basic Fujiwara reaction can befurther modified by mixing an organic base and water to form a one-phasereaction solution. In one embodiment, the organic base is selected fromthe group of tetraalkylammonium hydroxides includingmethyltributylammonium hydroxide, tetramethylammonium hydroxide,tetrabutylammonium hydroxide and tetrapropylammonium hydroxide.

The composition of the reagent mixture, reaction temperature and timingcan be carefully selected to improve the method by making adetermination of the concentrations of the four individual THMcomponents (as well as their total). This modification to the basicchemical method takes advantage of the different reaction kinetic andequilibrium profiles for the four THMs. That is, as part of theFujiwara-type reaction, the four THMs are converted to a colored productat different rates and to different extents of formation. For example,when a pyridine derivative such as 3-picoline is mixed with the solventsacetonitrile and water and treated with an organic base such astetramethylammonium hydroxide, then the reaction profiles can befollowed by monitoring the time resolved absorption of the product, asdepicted in FIG. 4 . As can be seen, the color development from thereaction of the two mixed bromo-chloro THMs reaches a maximum early att₁ (represented by a left-most vertical line within the area of thegraph 401). In contrast, chloroform reacts most slowly, with the coloredsolution becoming most intense at time t₂ (represented by a right-mostvertical line in FIG. 4 ). In principle, four measurements of thedevelopment in color of a THM/Fujiwara chemical reaction mixture couldbe used to deconvolute the absolute concentrations of the fourindividual THM components or species referred to earlier. This processwill be further explained below with reference to FIGS. 7-9 .

Another feature of the method and embodiments presented in thisdisclosure is the use of two calibration standards for the purpose ofmaintaining accuracy and repeatability in the determination of thespeciation of the four THMs in the water samples. A particularlybeneficial set of calibration standards is comprised of one containingonly CHCl₃, and another formulated with a mixture (not necessarily inequal proportions) of the three brominated THMs (CHCl₂Br, CHBr₂Cl andCHBr₃). This strategy takes advantage of the information taught in FIG.4 , which demonstrates that an early absorbance at time t₁ mostsignificantly corresponds to the quantitative sum of the threebrominated THMs, whereas the absorbance measurement at time t₂ reflectsthe concentration of all four THM components. Alternatively, a separatestandard may also be used for each brominated THM. In the act ofcalibrating the modified Fujiwara process in the disclosed apparatus,two time-resolved absorbance results (at t₁ and t₂) for each of the twocalibration standards at known concentrations are measured and recorded(for example in a database). These four time-resolved absorbance valuesare the coefficients necessary to construct the calibration “curves” ofthe Beer-Lambert Law which relates absorbances to concentrations. Thusfor an unknown sample of mixed THMs, the concentrations of CHCl₃ and theTTHMs can be calculated by mathematical solving a set of twosimultaneous equations based on two input variables (absorbancemeasurements at times t₁ and t₂) and the set of known absorbance values.

The measurement methodology can be further improved to solve for allfour THM concentrations by taking into consideration the premise thatthe relative speciation of the four THMs is a natural function of thekinetics of their formation in the water disinfection process (dependingon parameters such as the concentration and type of organic matter inthe water, pH, temperature, chlorine dosage and bromide levels in thewater). This principle is depicted graphically in FIG. 7 , whichrepresents the relationships between the speciation of the four THMsderived from measurement of 40 drinking water samples collected fromwater utilities geographically dispersed in the UK. For example, it isobserved for most disinfected drinking water samples whose CHCl₃ levelcontributes 30% to the total THM value (represented by the left-mostvertical line in FIG. 7 ), that the relative amounts of CHCl₂Br, CHBr₂Cland CHBr₃ are typically close to 35%, 28% and 7% respectively.Similarly, if the CHCl₃ level is 60% of the total THM levels in watersamples (see the right-most vertical line in FIG. 7 ), the same othercomponents are expected to be 27%, 12% and 1% in relative proportions.

By taking advantage of this natural speciation profile of THMs indrinking water samples, a method for the deconvolution of all four THMcomponents can be achieved based on as few as two different time-basedabsorbance measurements during the Fujiwara-type reaction; the firstmeasurement is performed at a relatively early stage (t₁) and the secondat a later time (t₂) (again, these are represented by the vertical lineswithin the graph area of FIG. 4 ). Thus, in at least one embodiment, thehalohydrocarbon measurement techniques discussed above are repeatedtwice for the purposes of identifying concentration of each THM speciesor component, as referenced above, based on time-dependent curve data aspresented in FIG. 4 . The optical measurements obtained at each time arelinked to the horizontal axis in the graph of FIG. 4 (based on elapsedtime since the reaction commenced), and the concentration of individualTHM components are determined from total chloroform and total “group”THM determinations.

This analytical and computational technique for the determination of thespeciation of THMs in drinking water, based on two absorbancemeasurements in a modified Fujiwara reaction mixture on an apparatuscalibrated in the above manner, has been demonstrated to be reliableover a wide range of THM speciation. For example, a heavily chlorinatedprepared mixture of THMs equivalent to a water sample at a total THMconcentration of 75.5 ppb (comprising 64.7 ppb CHCl₃, 9.9 ppb CHCl₂Br,0.8 ppb CHBr₂Cl and 0.1 ppb CHBr₃) was determined after 20 measurementsto contain an average TTHM value of 74.6 ppb (−1.2% accuracy and 0.5%RSD) and 86% CHCl₃ (64.2 ppb CHCl₃; −1.5% accuracy and 0.7% RSD). At theother end of the spectrum of THM speciation in drinking water, a heavilybrominated mixed THM sample equivalent to a total THM concentration of53.3 ppb in water (9.5 ppb CHCl₃, 21.4 ppb CHCl₂Br, 14.9 ppb CHBr₂Cl and7.5 ppb CHBr₃) was determined after 20 measurements to contain anaverage TTHM value of 53.8 ppb (+1.0% accuracy and 0.8% RSD) and 17%CHCl₃ (8.9 ppb CHCl₃; −6.5% accuracy and 2.9% RSD).

More specific implementations of an in-situ device, can operate asfollows:

-   -   a) the system purges a test sample at an elevated temperature,        preferably 60-70° C., to separate volatile hydrocarbons,        including THMs, from bulk sample volume;    -   b) the system then concentrates halohydrocarbons from a very        dilute sample onto an adsorbent trap material, enhancing        sensitivity and reducing bias; In one embodiment volatile        hydrocarbons, preferably THMs, are by this process continuously        adsorbed on a porous surface of carbopack and carboxen layers        (trap), or the porous surface medium can be derived from of        2,6-diphenylene oxide;    -   c) volatile hydrocarbons, preferably THMs, are then        quantitatively desorbed from the trap by heat (thermal        desorption) or quantitatively eluted with solvent from the        porous surface (solvent elution) into the reaction medium (i.e.,        a reaction mixture);    -   d) halohydrocarbons react with reaction mixture at elevated        temperature and form red color species; and    -   e) measurements are then made of the optical absorption of this        red color species to determine halohydrocarbon concentrations in        aqueous sample.

These features can be automated, e.g., performed under computer controlwith the entire measurement (and subsequent cleaning process) takingless than one hour (e.g., it will be recalled that in one embodiment,new measurements are taken at intervals of every hour). The baseprocesses referred to above can be performed more quickly and thus, inanother embodiment, the entire process can be completed in as little as15 to 20 minutes, or even more quickly.

Two such embodiments are discussed with reference to the attached FIGS.5 and 6 .

FIG. 5 is a schematic of one embodiment 501 of an in-situ analyticaldevice. During operation, a water sample enters a vessel 503, via atwo-way valve 505 and three-way valve 507 to a preset volume enforced bya level sensor (the sample amount is specified depending upon therequired detection limit and historic makeup of the sample). The watersample is heated in vessel 503 to a predetermined temperature setting tofacilitate release of the volatile halohydrocarbons. The air or nitrogengas from two-way valve 509 is then bubbled through the sample. Air ornitrogen gas then carries volatile halogenated hydrocarbons through adryer 511, where any moisture in the gas is removed. Gas passes throughtwo three-way valves 513 and 515 and enters into a trap (column) 517that contains layers of material that adsorbs volatile halohydrocarbons,such as THMs. The gas then is vented after passing through valve 531.Then, valve 515 is opened toward a chemical reservoir 519. Using arotary selector valve 521, a predetermined amount of pyridine derivativereagent A and the optional organic solvent B is introduced to thereservoir 519 by an electronically-controlled syringe 523. Syringe 523then sends the solution into a flow cell 525 of an optical spectrometer.Light from a light source 527 passes through the solution in the flowcell while a detector 529 measures the intensity of the transmittedlight. The measurement taken from this solution is called a “blank”reading. The solution is pulled back to the syringe 523 and then pushedto the reservoir 519.

The trap (column) 517 is then heated to a temperature suitable forvolatilizing the analytes and air or nitrogen is swept through thecolumn. This causes the halogenated hydrocarbon to be desorbed from thecolumn and bubbled into solution in the reservoir 519. The path followedby low-pressure air or nitrogen is from a regulator 533, through thecolumn and to the reservoir 519 via valve 515. At the end of desorption,the solution which contains halogenated hydrocarbons and an organicreagent C is drawn back to the syringe 523 and is mixed well. Thereaction medium in the reservoir 519 at this point contains the pyridinederivative A, the optional organic solvent B, the strong organic base C,and the halohydrocarbons (in unknown quantities).

The reaction mixture is then pulled into syringe 523 via the rotaryselector valve 521 from the reservoir 519. The solution from the syringe523 is pushed to a heated reservoir or reaction vessel 535, where thetemperature is fixed (a particularly useful range is 70-80° C.). Thesolution stays in the reaction vessel for a predetermined amount oftime, during which the reaction begins and progresses, activated by theconsequent heating. The clear solution in the heated reservoir 535begins to turn to the color red and, after first specified time, t₁, thesolution is pulled back into the flow cell 525 where the solution iscooled, thereby halting the reaction. The optical intensity is thenmeasured at time t₁; in one embodiment, this first reading is taken atan interval of 60 to 120 seconds following initiation of the reaction.As soon as the reading has been taken, the solution is pushed back tothe reaction vessel 535 and stays there again for another specifiedamount of time. The solution is then once again pulled back to the flowcell where the solution is again cooled before a second intensitymeasurement is taken at time t₂; again, in one embodiment, this secondreading is taken at an interval of 600 to 1200 seconds after initiationof the reaction. The solution is then drawn back to the syringe 523 andsent to a chemical waste drain or container 537 through a port of therotary selector valve 521.

Two absorbance values at times t₁ and t₂ are calculated using theoptical transmission measurements represented by the blank reading andthe measurements taken at times t₁ and t₂. These two absorbances areused to determine two concentrations of halogenated hydrocarbons,specifically chloroform and the total THM in the unknown on-line watersamples in the manner presented above.

The system is returned to a ready state by routine cleaning maintenance.The water sample in the purge vessel 503 is emptied by applyingpressurized air or gas through valve 509, and opening the valve 539 tothe waste water drain 541. The components employed in the chemicalreaction, specifically the flow cell 525, the syringe 523 and thereservoirs 519 and 535, are cleaned with either the organic solvent B,or a dedicated cleaning reagent (such as THM-free water or anotheragent) D. The trap 517 is treated to a bake process at an elevatedtemperature (such as 240° C.) and swept with gas/air from regulator 533,through valves 531 and exiting out the vent of the reservoir 519.

The analytical system embodiment just presented has the capability tointroduce standards for the calibration and validation of the process.In the case of THM determination, one standard E is for chloroform andanother standard F is for the three brominated THMs. To perform anon-line calibration, the vessel 503 is filled with a known amount ofTHM-free water (e.g., distilled water, or water purged free of THMs withair through valve 509 and vented out valve 513). A known concentrationand amount of chloroform standard E and/or brominated standard F isadded to the vessel 503 via valve 507 by syringe 523 drawn through therotary selector valve 521. The process set up is as described earlier.The absorbances of the red color of the calibration reaction solution attimes t₁ and t₂ are recorded and absorbance values are constructed fromthe slopes of the concentration vs. absorbance relationships. Thiscalibration slope may be used to quantitatively determine theconcentration of halohydrocarbons in unknown on-line water samples inthe manner presented above.

FIG. 6 is a schematic of another embodiment 601 of an analytical systemwhich halohydrocarbons are concentrated on a porous material and elutedwith solvent.

During operation, a water sample enters a vessel 603, via a two-wayvalve 605 and the three-way valve 607. The sample in vessel 603 isheated to a predetermined temperature setting. Air or nitrogen gas fromtwo-way valve 609 is bubbled through the sample. The gas then carriesthe volatile halogenated hydrocarbons through three-way valves 639 and611 into a packed column 613 containing layers of adsorbent material toadsorb volatile hydrocarbons, such as THMs. This purge gas passesthrough a port of a rotary selector valve 615, and vented through valve617 connected to an opening in the syringe 619. After an appropriatetime for the purge transfer of the halohydrocarbon analytes from thewater sample to the trap column 613, valve 611 is then opened toward thechemical reservoir 621.

Using the rotary selector valve 615, a predetermined amount of organicsolvent B, such as acetonitrile, is drawn into anelectronically-controlled syringe 619 and transferred through the column613. The halogenated hydrocarbons are quantitatively eluted from thecolumn and collected in the reservoir 621. A fixed amount of pyridinederivative A is mixed into the reservoir 621 with syringe 619 throughports of the rotary selector valve 615 and valve 623. The solution isthen mixed by pulling the solution to the syringe 619 and then pushingthe solution back to the reservoir 621. The organic solvent withhalogenated hydrocarbons and pyridine derivative is then drawn back tothe syringe 619 and sent to a flow cell 625. The light from a lightsource 627 passes through the solution in the flow cell 625 while adetector 629 measures the intensity of the transmitted light. Themeasurement taken from this solution is, once again, called a “blankreading.” The solution is pulled back to the syringe and pushed to backto the reservoir.

For the ensuing reaction-dependent measurements, the reaction mixture ispulled into the syringe 619 via the rotary selector valve 615. A fixedamount of the base reagent C is introduced into syringe 619 and thesolution is mixed well. The reaction medium in the syringe at this pointcontains the organic solvent B, pyridine derivative A, the strongorganic base C, and the halohydrocarbons (in unknown quantities). Thesolution is pushed into a heated reservoir or reaction vessel 631, wherethe temperature is fixed at a predetermined point (a particularly usefulrange is 70-80° C.). The solution stays in the reaction vessel for apredetermined amount of time. Beginning as a clear solution, under theinfluence of the heat, the solution begins to react and turns to red.After a first specified time, t₁, the solution is pulled back into theflow cell 625 where the solution is cooled, halting the reaction beforethe intensity measurement is taken. The optical intensity is then readout at time 0. The solution is pushed back once again to the heatedreaction vessel 631 and stays there again until another specified time,t₂. Once that second specified time arrives, the solution is againpulled back to the flow cell 625 where it is again cooled before theintensity is measured at time t₂. Finally, the solution is drawn back tothe syringe 619 and sent to a chemical waste drain or container 633.

Two absorbances are calculated using the measured light intensitiesprovided by the blank reading and optical measurements at times t₁ andt₂. These two absorbances are used to determine two concentrations ofhalogenated hydrocarbons, specifically chloroform and the total THMs inthe unknown water samples in the manner presented above.

As with the embodiment of FIG. 5 , the analytical system of the systemof FIG. 6 is returned to a ready state by routine cleaning maintenance.The water sample in the purge vessel 603 is emptied by applyingpressurized air or gas through valve 609, and opening the valve 635 tothe waste water sample drain 637. The components employed in thechemical reaction, specifically the flow cell 625, the syringe 619 andthe reservoirs 621 and 631, are cleaned with either the organic solventB, or a dedicated cleaning reagent (such as THM-free water) D. The trap613 is treated to a process that evaporates the residual solvent bysweeping it with gas/air through valves 617 and rotary selector valve615; the hot gas is then removed through the vent of the reservoir 621,via valve 611.

As with the embodiment of FIG. 5 , the analytical system of the systemof FIG. 6 also has the capability to introduce standards for thecalibration and validation of the process. In the case of THMdetermination, one standard E is for chloroform and another standard Fis for brominated THMs. To perform an on-line calibration, vessel 603can be filled with a known amount of sample water and made THM-free bypurging THM using air flowing in through valve 609 and venting outthrough valve 639. A known concentration and amount of chloroformstandard and/or brominated standard is added to the vessel by thesyringe 619 drawn through the rotary selector valve 615, and in to thepurge vessel through valve 607. The process set up is as describedearlier. The absorbances of the red color of the calibration mixture arerecorded at times t₁ and t₂, and the relationship between absorbancesand known concentrations is evaluated. The resultant slope may be usedto quantitatively determine the concentration of halohydrocarbons inon-line samples in the unknown on-line samples in the manner presentedabove.

As introduced above, some embodiments presented by this disclosure maybe used to resolve individual THM species based on two or more opticalmeasurements. This principle was introduced above by reference to FIG. 7, and is further discussed below with reference to FIGS. 8 and 9 .

As mentioned, FIG. 7 provides a sample graph 701 that depicts therelationships of the relative ratios of the four THMs, while FIG. 8provides a graph 801 that shows absorbance variation for individual THMspecies in dependence upon reaction time. Through the measurement ofabsorbance of two different points in the reaction, concentration ofeach THM species can be derived from the total THM measurementintroduced above, and this information can be used in conjunction withthe data presented in FIGS. 7-8 to determine individual THM speciesconcentrations. This process is explained with reference to FIG. 9 .

In particular, FIG. 9 further provides a flow chart 901 illustratingsteps that can be used to determine these individual concentrations.

-   -   1) Selection of Standards (903): Appropriate calibration        standards of individual THMs, or alternatively, a mixture of        THMs, are selected. A particularly useful two-STD configuration        comprises one standard containing chloroform only (labeled        ‘Cl3’), and the other containing a mixture of the three        brominated THMs (labeled ‘Br1-3’) (the ideal standards reflect        the most probable composition or ratio expected in the water        samples to be analyzed).    -   2) System Calibration (the establishment of time-dependent        absorptivity coefficients for each standard) (905): Using the        same in-situ device that will be used to take “real-time”        samples, a known quantity of each standard is added in an        independent process to a THM-free water sample in the purge        vessel, and the method described above        (purge/trap/desorb/reaction) is performed upon this sample, to        measure absorbance at each of two reaction times t₁ and t₂.        According to the Beer-Lambert Law, an absorptivity coefficient ε        (epsilon) at each time is calculated: ε_(t)=A/l·c (where        A=Absorbance, l=optical path length in the flow cell, and        c=concentration). These values correspond to the values enclosed        within the circles in FIG. 8 , and are respectively labeled as        ^(Cl3)ε_(t1), ^(Cl3)ε_(t2), ^(Br1-3)ε_(t1) and ^(Br1-3)ε_(t2).        The values obtained are stored (e.g. in a database) for use        later.    -   3) Sample Analysis (907): For in-line or “live” measurements,        that is, to determine unknown THM concentrations in a water        sample, an aqueous sample is taken (e.g., from a potable or        other water supply, as described earlier) and subjected to the        complete process (purge/trap/desorb/chemical reaction) to        measure the two optical absorbances at time t₁ and t₂ (A_(t1)        and A_(t2)).    -   4) TTHM and % CHCl₃ Concentrations Determined (909): One then        solves for the concentrations of chloroform and brominated THMs        in the sample ([CHCl₃] and [CHBr₁₋₃Cl₂₋₀]) by solving the        following two simultaneous equations:        [CHBr₁₋₃Cl₂₋₀]=(A_(t1)×^(Cl3)ε_(t2)−A_(t2)×^(Cl3)ε_(t1))/(^(Br1-3)ε_(t1)×^(Cl3)ε_(t2)−^(Br1-3)ε_(t2)×^(Cl3)ε_(t1))  (1)        [CHCl₃]=(A_(t1)−[CHBr₁₋₃Cl₂₋₀]×^(Br1-3)ε_(t1))/^(Cl3)ε_(t1)  (2)        where ^(Cl3)ε_(t1), ^(Cl3)ε_(t2), ^(Br1-3)ε_(t1), and        ^(Br1-3)ε_(t2) represent the stored calibration data obtained        from step (2), above. The total THM concentration [TTHM] is        equal to [CHBr₁₋₃Cl₂₋₀]+[CHCl₃], and the percentage of        chloroform in the sample is equal to 100×        [CHCl₃]/([CHBr₁₋₃Cl₂₋₀]+[CHCl₃]).    -   5) Calculation Of Speciation Of Each Individual THM (911): To        deduce the individual concentrations of the three brominated        THMs in the water sample ([CHBrCl₂], [CHBr₂Cl], and [CHBr₃]),        the values obtained for [CHCl₃] and [TTHM] from step (4) are        compared using the information presented in FIG. 7 , and used to        solve for each individual brominated species.

This procedure for determining the individual concentrations of all fourTHM components in potable water samples can be demonstrated by applyingthe analysis to the two exemplary samples discussed earlier.

As can be seen from this discussion, embodiments presented hereinprovide a novel, automated way to calculate each individual THM speciesof interest. As alluded to earlier, a control system may, as part of anin-situ device, part of a local area network (“LAN”) or over a wide areanetwork (“WAN,” e.g., the internet), automatically monitor a watersupply and take remedial action, for example, by sounding or otherwisetriggering an alarm, or by using an electronic control system and thefeedback provided by periodic measurements to adjust chemical treatmentupstream in a water sanitation or other process.

As mentioned, the embodiments presented in this disclosure facilitate adevice that can be installed in the field near the water distributionsystem, that can collect and analyze samples on-line, avoiding the needto collect samples in vials and deliver them to an offsite laboratoryfor analysis. The system may be run continuously, 24 hours per day,unattended, with a warning indication or other action if contaminantsexceed a specified limit, responsive to a detected maintenancecondition, or on another ad-hoc basis.

FIG. 10 provides a system diagram 1001 used to explain a method ofremotely monitoring one or more in-situ mechanisms or devices. Inparticular, FIG. 10 is divided into middle, left and right portions(1003, 1005 and 1007) that respectively represent (a) an on-line orother business that for a fee may automatically monitor one or morewater supplies, (b) one or more clients of the business, e.g., one ormore municipal water companies, and (c) a regulatory authority or otherentity that is to monitor or receive reporting of compliance of any oneof the water supplies. FIG. 10 illustrates two hypothetical clients 1009and 1011, each of which may be taken to be a water company, each ofwhich may have one or more in-situ devices 1013 for monitoring aparticular portion of a water delivery network (only one in-situ deviceis numerically labeled to simplify the illustration). In this regard, itshould be assumed that the method (e.g., the business) is toautomatically and/or remotely collect measurement data for the purposesof logging THM data for compliance reporting or other purposes; to thiseffect, the business 1003 includes a supervisory control mechanism 1015,depicted as one or more computers running software 1017 (e.g., a serversystem), with this system interfacing both with each client (via aclient-side web interface 1019), and with a regulatory authority 1021(via a regulatory side interface 1023). In one embodiment, theregulatory side web interface may provide a portal for regulatoryauthorities to remotely audit current and past individual water supplyoperations, with further ad-hoc tests being initiated as required, andwith the business interacting with regulatory authorities on behalf ofeach client, if desired or appropriate, in a manner transparent to eachclient. Each interface 1019/1023 may permit different access levels andpresent different authentication requirements (e.g., a specific type orlevel of PKI authentication). For example, because the client sideinterface may be used for automated communication with each in-situdevice 1013, each such device may be made to have an embeddedcryptographic key for purposes of authentication; on the other hand,because regulatory interaction may involve aggregated, relativelysensitive data, two-factor or other authentication requirements may beused as a predicate for individual access by a remote human user.Regardless of the interface formats, the supervisory system can beconfigured to perform a number of functions, depicted at the middle ofFIG. 10 , thereby relieving the clients 1009 and 1011 from the need toperform these functions themselves, and minimizing the need for on-sitepresence or inspection by regulatory authorities. As indicated byreference numeral 1025, the method may include periodically receivingtest data from each one of the plural in-situ devices 1013 via theclient-side interface 1019; each instance of test data may represent anautomated process that is initiated by the specific device 1013, and/orthe supervisory system 1015 may also selectively initiate tests. Forexample, if it is determined that a specific THM concentrationdetermined from a test is out of normal bounds, an ad hoc test may becommanded by the supervisory control system, as indicated by referencenumeral 1026. The supervisory control system may perform data basemanagement (1027), indexing each set of test data by particularprovider, time and date, last known calibration, and any other desireddata. As indicated by blocks 1031, 1033, 1035 and 1037, the supervisorycontrol system (or a different electronic control system) may also testfor and/or respond to maintenance events, generate alarms or takeprocess control actions responsive to comparison of THM levels againstthresholds, and generate automatic compliance reports either for theregulatory authority 1021 or a particular client 1009 or 1011. Asfurther depicted by a dashed-line, optional block 1029, if desired, rawdata may be reported to the supervisory control system 1015, with totaland/or individual species THM calculations being performed by thesupervisory control system 1015, on a remote basis.

As should be apparent from this description, the methods and devicesprovided above, by facilitating real-time, relatively same, automatedTHM measurement, provide for new advances not only in the measurementprocess, but also in terms of compliance and accountability, potentiallychanging the way in which water companies and regulatory authorities dobusiness.

Various alternatives to the foregoing techniques will readily occur tothose having skill in the art. To pick just a few examples, techniquesmentioned above may be applied using other types of detected opticalactivity (e.g., other than change in visible color intensity), andhalohydrocarbon extraction may be accomplished using mechanisms otherthan an adsorbent medium. To pick another example, the method ofbusiness described above may be applied with or without modifiedFujiwara-type chemistry. Many other variations also exist. Accordingly,the foregoing discussion is intended to be illustrative only; otherdesigns, uses, alternatives, modifications and improvements will alsooccur to those having skill in the art which are nonetheless within thespirit and scope of the present disclosure, which is limited and definedonly by the following claims and equivalents thereto.

We claim:
 1. An apparatus to monitor halohydrocarbon presence in a waterdistribution system, the apparatus comprising: circuitry to communicatewith a network; a sample extraction mechanism to from-time-to-time drawwater samples from the water distribution system; a reservoir for astandard; a measurement system to obtain measurements of halohydrocarbonconcentration in respective ones of the water samples; an electroniccontrol system to control the sample extraction mechanism and themeasurement system so as obtain the measurements, control the apparatusso as to from-time-to-time perform calibrations using the standard, andrenew the measurement system for ensuing ones of the measurements;wherein the electronic control system is to control the apparatus toobtain the measurements according to timing that is externally dictatedvia the network.
 2. The apparatus of claim 1, wherein the circuitry isto connect to a wide area network (WAN), wherein the electronic controlsystem is to receive instruction from the WAN to dynamically draw awater sample from the water distribution system and to measurehalohydrocarbon concentration in the dynamically-drawn water sample, andwherein the apparatus is further to transmit via the WAN at least oneresult dependent on measurement of halohydrocarbon concentration in thedynamically-drawn water sample.
 3. The apparatus of claim 1, wherein thecircuitry is to connect to a wide area network (WAN), wherein theelectronic control system is to receive instruction from the WAN todynamically calibrate the measurement system, and wherein the apparatusis further to transmit via the WAN at least one result dependent on thedynamic calibration of the measurement system.
 4. The apparatus of claim1, wherein: the measurement system comprises an adsorption medium; themeasurement system is to transfer controlled volumes of water from thesamples to the adsorption medium to separate halohydrocarbons from thecontrolled volumes of water and is to combine the separatedhalohydrocarbons with one or more reagents to cause color development ina manner dependent on amount of the separated halohydrocarbons; and achromatograph to generate measurements of halohydrocarbon concentrationsin the controlled volumes of water according to developed color.
 5. Theapparatus of claim 4, wherein the reservoir is a first reservoir,wherein the apparatus comprises a second reservoir, wherein the one ormore reagents comprise a pyridine derivative, and wherein themeasurement system is to transfer pyridine derivative from the secondreservoir to as to combine the separated halohydrocarbons with thepyridine derivative.
 6. The apparatus of claim 4, wherein the one ormore reagents comprise a pyridine derivative characterized by a pyridinestructure with one or more substitutions of hydrogen at the carbon atomsof the pyridine.
 7. The apparatus of claim 4, wherein the measurementsystem is to for at least one of the water samples perform plural,time-separated measurements of developed color and wherein the apparatusis to calculate concentrations from the time-separated measurementsrespective to at least two different halohydrocarbon species.
 8. Theapparatus of claim 1, wherein the measurement system is to for at leastone of the water samples perform plural measurements and wherein theapparatus is to calculate concentrations from the plural measurementsrespective to at least two different halohydrocarbon species.
 9. Theapparatus of claim 1, further comprising digital memory, wherein theelectronic control system is to store in the digital memory results ofeach of the measurements including, for each one of the measurements, atleast a time that the one of the measurements was performed and ameasure of halohydrocarbon concentration detected by the one of themeasurements.
 10. The apparatus of claim 1, wherein the electroniccontrol system is transmit to the network results of each one of themeasurements including at least, for each one of the measurements, atime that the one of the measurements was performed, a measure ofhalohydrocarbon concentration detected by the one of the measurements,and at least one of a location or an identification of the apparatus.11. The apparatus of claim 1, wherein the electronic control system isto control the apparatus such that at least one of the calibrations isperformed as a spike test, on the basis of both of the standard and oneof the samples.
 12. The apparatus of claim 1, wherein the standardcomprises a predetermined concentration of halohydrocarbons.
 13. Theapparatus of claim 1, wherein the standard comprises at least one ofCHCl₃, CHBrCl₂, CHBr₂Cl and CHBr₃.
 14. An apparatus to monitorhalohydrocarbon presence in a water distribution system, the apparatuscomprising: circuitry to communicate with a network; a sample extractionmechanism to from-time-to-time draw water samples from the waterdistribution system; a first reservoir for a standard and a secondreservoir for a reagent; a measurement system to obtain measurements ofhalohydrocarbon concentration in respective ones of the water samples,wherein the measurement system is to measure halohydrocarbonconcentration by creating a reaction between halohydrocarbons separatedfrom the samples and the reagent and by measuring an optical property ofthe reaction; an electronic control system to control the sampleextraction mechanism and the measurement system so as obtain themeasurements, control the apparatus so as to from-time-to-time performcalibrations using the standard, and renew the measurement system forensuing ones of the measurements; wherein the electronic control systemis to control the apparatus so as to obtain the measurements accordingto timing that is externally dictated via the network.
 15. The apparatusof claim 14, wherein the reagent comprises a pyridine derivative andwherein the measurement system is to transfer pyridine derivative fromthe second reservoir so as to combine the separated halohydrocarbonswith the reagent.
 16. The apparatus of claim 14, wherein the reagent isa pyridine derivative characterized by a pyridine structure with one ormore substitutions of hydrogen at the carbon atoms of the pyridine. 17.The apparatus of claim 14, wherein the circuitry is to connect to a widearea network (WAN), wherein the electronic control system is to receiveinstruction from the WAN to dynamically draw a water sample from thewater distribution system and to measure halohydrocarbon concentrationin the dynamically-drawn water sample, and wherein the apparatus isfurther to transmit via the WAN at least one result dependent onmeasurement of halohydrocarbon concentration in the dynamically-drawnwater sample.
 18. The apparatus of claim 14, wherein the measurementsystem is to for at least one of the water samples perform plural,time-separated measurements and wherein the apparatus is to calculateconcentrations from the plural, time-separated measurements respectiveto at least two different halohydrocarbons species.
 19. The apparatus ofclaim 14, wherein the sample extraction system is to connect in-line toa distribution element of the water distribution system to draw thewater samples therefrom.
 20. The apparatus of claim 14, wherein theelectronic control system is to control the apparatus such that at leastone of the calibrations is performed as a spike test, on the basis ofboth of the standard and one of the samples.
 21. The apparatus of claim14, wherein the at least one standard comprises at least one of CHCl₃,CHBrCl₂, CHBr₂Cl and CHBr₃.
 22. An apparatus to monitor halohydrocarbonpresence in a water distribution system, the apparatus comprising:circuitry to communicate with a server via Internet; a sample extractionmechanism to from-time-to-time draw water samples from the waterdistribution system; a first reservoir for a standard and a secondreservoir for a reagent; a measurement system to obtain measurements ofhalohydrocarbon concentration in respective ones of the water samples,wherein the measurement system is to measure halohydrocarbonconcentration by creating a reaction between halohydrocarbons separatedfrom the samples and the reagent and by measuring an optical property ofthe reaction; an electronic control system to control the sampleextraction mechanism and the measurement system so as obtain themeasurements, control the apparatus so as to from-time-to-time performcalibrations using the standard, and renew the measurement system forensuing ones of the measurements; wherein the electronic control systemis to control the apparatus so as to obtain the measurements accordingto timing that is externally dictated via the network.
 23. The apparatusof claim 22, wherein the electronic control system is to receiveinstruction from the server to dynamically draw a water sample from thewater distribution system and to measure halohydrocarbon concentrationin the dynamically-drawn water sample, and is further to provide to theserver at least one result dependent on measurement of halohydrocarbonconcentration in the dynamically-drawn water sample, and wherein theelectronic control system is to receive instruction from the server todynamically perform a calibration dependent on the standard and to isfurther to provide to the server at least one result dependent on thedynamically-performed calibration.